I'm not clear what you're describing here. Aren't the whips on the G3 Tx units the same as on the Rx units? I've not seen this. Can you post a pic of how the whip is connected to the chassis?
I'm making (and selling) SMA adapters for the Sennheiser bodypacks, and haven't seen this, but obviously would want to make sure what I'm making isn't incompatible with those units.